Maker Pro
Maker Pro

hp5326a timer-counter

R

RoV

Jan 1, 1970
0
Hi all,

I have found an old hp5326a that I would like to repair because I like to
restore old equipment.
Almost everything works apart input A. The problem seems to stay on the
input board p/n 05327-60034, because even swapping the two boards connected
to it to handle the triggering for A and B, the problem remains on A.
By comparing channels A and B, I see that in the working channel the trigger
level pot changes a voltage on the connector going to the respective trigger
board, while this doesn't happen on the other channel. The corresponding
line goes to a metal can, 6 pin chip marked 5-334.
Unfortunately I couldn't find the schematic on the net (for free or at least
cheaper respect to what I payed the instrument...). Neither I was able to
find any info about the chip: I tried something like 1855-0344 but I later
discovered that, in hp numbering, xxx5 is never used for ICs.

I wonder if someone can help...
(my real mail is on the web page)

Regards,
 
C

Caesar Valenti

Jan 1, 1970
0
RoV said:
Hi all,

I have found an old hp5326a that I would like to repair because I like to
restore old equipment.
Almost everything works apart input A. The problem seems to stay on the
input board p/n 05327-60034, because even swapping the two boards connected
to it to handle the triggering for A and B, the problem remains on A.
By comparing channels A and B, I see that in the working channel the trigger
level pot changes a voltage on the connector going to the respective trigger
board, while this doesn't happen on the other channel. The corresponding
line goes to a metal can, 6 pin chip marked 5-334.
Unfortunately I couldn't find the schematic on the net (for free or at least
cheaper respect to what I payed the instrument...). Neither I was able to
find any info about the chip: I tried something like 1855-0344 but I later
discovered that, in hp numbering, xxx5 is never used for ICs.

I wonder if someone can help...
(my real mail is on the web page)

Regards,
You had the right idea. The p/n is 1855-0334 (not 0344). It is not an
IC, but rather a dual FET, hence the 6 pins. I think the manufacturer is
Siliconix.
Unfortunately, I could not (easily) find a cross-reference, so I do not
know much about it....but there are a couple dozen hits in Google....try
that.
cv
 
J

Jorgen Lund-Nielsen

Jan 1, 1970
0
Caesar said:
You had the right idea. The p/n is 1855-0334 (not 0344). It is not an
IC, but rather a dual FET, hence the 6 pins. I think the manufacturer is
Siliconix.
Unfortunately, I could not (easily) find a cross-reference, so I do not
know much about it....but there are a couple dozen hits in Google....try
that.
cv

http://www.sphere.bc.ca/test/hp-parts/hpparts4.html

scroll down to 1855-0334

but beware, 24$/pice (Canadian $)


Jorgen
dj0ud

HTH,

Jorgen
 
R

RoV

Jan 1, 1970
0
You had the right idea. The p/n is 1855-0334 (not 0344). It is not an

Thank you Caesar and Jorgen.
Once I understood it was a dual FET, I tried to take some measurements with
the scope to fix the source of the problem. But it proved impossible,
because the board is located behind the front panel, with other four boards
orthogonally placed behind it (two of them, the trigger boards, are inserted
in this one and also on the bottom backplane. So I decided to try to remove
the front panel to access the back of the board. Finally I was ready, in a
very temporary setup (potentiometers and commutators hanging around,
protected with plastic bags from shorts...). I turned the instrument on and
to my surprise it worked. I was happy, but a bit disappointed for the time
required to dismount it!
I finally realized that the trigger level pot on input channel A (the failed
one) did non work when its axis was pressed; probably I accidentally put it
to work by pulling it to remove the knob! Unfortunately, it is quite a
special kind of pot, but I think I can leave it as it is now that I know the
trick.
Fortunately, once remounted, the instrument kept on working. It reads up to
85MHz, not bad for being rated 50MHz.
In any case, I hope I will find the service manual sooner or later.

Regards,
Roberto
 
Top